Most motor vehicle doors generally have an outer door panel or skin and an inner door panel in spaced relation such that a door cavity is defined. Disposed within the door cavity are various door systems such as locking mechanisms and lowerable window actuating means. Without further structural reinforcement, these hollow motor vehicle doors are not particularly resistant to permanent deformation by side impacts. That is, when a motor vehicle door of this type is struck during a collision or the like the inner and outer door panels offer only limited resistance to side intrusion. Hence, it will be appreciated that there is a need for structurally reinforced motor vehicle doors to provide greater impact resistance.
Several impact or intrusion-resistant devices and reinforced vehicle doors have been proposed by others such as that disclosed in U.S. Pat. No. 3,868,796 wherein it is suggested that a large foam-filled corrugated panel welded to the outer door skin provides increased impact resistance to a vehicle door. Similarly, in U.S. Pat. No. 3,964,208 a vehicle door is proposed which has an inner door panel that crosses the plane of the lowerable window and abuts the outer door panel. The inner door panel has an aperture through which the window passes as it is lowered. In one configuration, the region of the inner panel which abuts the other panel is corrugated such that voids are defined which may be filled with a foamed material. In U.S. Pat. No. 4,090,734, an undulated impact beam made of steel is disclosed upon which metal plates may be mounted to form a hollow structure. However, these devices suffer from a number of drawbacks ranging from high mass characteristics to complex manufacturing processes. Moreover, other known reinforcing means such as transverse hollow tubes and the like have proven inadequate due to their expense, excessive weight, multiple-piece construction and their inability to be adapted to various door configurations.
Those skilled in the art will understand that side-impact resistance of motor vehicle doors is subject to federal certification. For federal certification, side intrusion of vehicle doors is usually measured using an hydraulic ram which is pressed into the outer door panel. The load required to penetrate the door a preselected depth or distance such as 6 inches, 12 inches or like is determined and the results are compared to the federal standards. In order to comply with these federal standards, a vehicle door must demonstrate a certain minimum degree of side-intrusion resistance.
Although large, heavy, structural reinforcements provide increased side-intrusion resistance, they also add to the total vehicle weight and usually increase material production costs. Therefore, it would be desirable to provide a lightweight, compact door beam designed to easily fit within a vehicle door cavity. By providing a strong yet lightweight door beam, total mass savings could be achieved. In addition, it would also be desirable to provide such a door beam which can be easily fabricated from a minimum number of parts. Ideally, such a beam would be adaptable to various door designs and could be easily altered to provide a range of strengths. The present invention provides such an impact or intrusion door beam having the aforementioned desirable characteristics and features.